1. Field of the Invention
The present invention relates to an image forming apparatus.
2. Description of the Related Art
Fixing devices provided in electrophotographic image forming apparatuses are of two types: roller-type fixing devices that include upper heating rollers and lower pressing rollers (including heating rollers), and fixing-belt-type fixing devices that operate with more decreased fixing temperature and include endless fixing belts extended and rotated between a plurality of belt conveying rollers. Each type of the fixing devices fix an unfixed toner image to a transfer material such as a paper sheet by using heat and pressure while the transfer material passes through a nip formed by pressure contact between a fixing member such as a fixing roller and a pressing member such as a pressing member. Furthermore, the fixing member is provided with a cleaning device such as a take-up cleaner web to clean up residual toner and the like attached to the fixing member.
As described above, the toner image is fused and fixed onto a recording material at the nip portion. However, unfixed toner remains attached to the fixing member, and in some cases, some residual toner is not cleaned up by the above-mentioned cleaning device and remains attached as an image history, or a residual image that is not wiped out, on the fixing member. Conventionally, the fixing member is provided with a release-agent supply device that supplies release agents to reduce the residual toner attached to the fixing member.
To solve the above problems, Japanese Patent Application Laid-open No. H10-301431 for example discloses a technology in which a fixing device including a fixing member, formed of a heating member and a pressing member is provided with a release-agent supply device that can uniformly and stably supply release agents onto a surface of at least one of the heating member and the pressing member of the fixing device. Furthermore, a technology for cleaning a surface of the fixing member by using a solid-black toner image, i.e., a cleaning sheet, is disclosed in, for example, Japanese Patent Application Laid-open No. 2004-317929. More specifically, the cleaning sheet is inserted into a nip portion so as to be in contact with the surface of the fixing member and to be heated. Accordingly, an adhesive property of a cleaning layer is increased, thereby allowing paper dust, toner, and the like attached to the fixing member to adhere to the cleaning layer. As a result, the surface of a fixing roller is cleaned.
However, in the technology disclosed in Japanese Patent Application Laid-open No. H10-301431, residual toner that has not been cleaned up may be attached to the fixing member at any portions of an outlet of the nip portion, leading to fine irregularities on the fixing member. Furthermore, in the technology disclosed in Japanese Patent Application Laid-open No. 2004-317929, while the residual toner is removed from the fixing member by utilizing the adhesive property of the cleaning layer, some residual toner may not be removed by the cleaning sheet and may be attached to the fixing member, leading to fine irregularities on the fixing member. Such fine irregularities on the fixing member make it difficult to eliminate and reduce uneven gloss that may occur when a toner image is fixed to a next transfer material as a next printing object.